CN115328343A - Touch panel and method for driving touch panel - Google Patents

Abstract

A touch panel and a driving method of the touch panel are disclosed. A touch panel includes arranged touch electrodes and a driver IC connected to each sensor electrode. The plurality of touch electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected (such as a finger). The driver IC alternately or sequentially applies a driving voltage to the sensor electrodes of the plurality of groups, detects a capacitance of each sensor electrode, and detects whether there is a touch based on the detected capacitance.

Description

Touch panel and method for driving touch panel

Cross Reference to Related Applications

This application claims the benefit of Japanese patent application No. 2021-80233, filed on 11/5/2021, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present disclosure generally relates to a touch panel and a driving method for the touch panel.

Background

In the touch panel, a driving signal is applied to a touch electrode in order to sense a touch. The driving signal is composed of a pulse signal having a predetermined frequency, and is a cause of electromagnetic interference (EMI). As an electronic device, the touch panel must maintain EMI at a certain level or lower.

Generally, the causes of electromagnetic interference (EMI) from digital circuits are: 1) A spike current flowing through the signal line in response to a low/high transition of the digital signal; 2) A penetration current flowing in the IC circuit when a digital signal is output from the IC circuit; 3) The decoupling capacitors of the IC circuits do not work adequately; 4) Common mode current caused by vulnerability of signal Ground (GND) of a device on which the IC circuit is mounted; and so on.

The touch panel outputs a pulse signal from the driver IC to the touch panel electrode to perform touch detection. Accordingly, a spike current caused by the pulse signal flows through a wiring connecting the driver IC and the touch panel electrode, and thus, a driving signal and a signal line of the touch panel may become a cause of electromagnetic interference (EMI). In the display device, the touch panel is arranged on the display surface side, and because of this, when an electromagnetic shield or the like is arranged on the touch panel to prevent electromagnetic interference (EMI), there are problems that the touch detection accuracy is lowered and the display visibility is adversely affected. In addition, in order to arrange filter elements (such as filter beads) for pulse signals of various lines, a large number of filter elements are required. Arranging such filter elements in a limited space is difficult and may affect the touch detection accuracy. Therefore, a countermeasure different from the electromagnetic shield or the filter element is required to prevent electromagnetic interference (EMI) to the touch panel.

As a measure for reducing radiated electromagnetic noise caused by operation of the touch panel, a driving method including switching a driving frequency has been proposed. For example, a touch display device described in japanese patent No. 6501750 includes a display mode for displaying an image and a touch mode for detecting a touch position. This driving method divides the touch pattern period into a plurality of unit touch periods. This driving method changes the frequency of the touch driving signal from the frequencies of the driving signals in the other unit touch periods and drives the electrodes in each unit touch period, and applies an idle driving signal to all the other electrodes when the touch driving signal is output to any one of the electrodes.

The touch display device described in U.S. patent application publication No. 2019/0235663 includes a plurality of display periods within one frame, switches and displays a display region in each display period, and detects a touch in a non-display region.

In addition, "43inch UHD Digital home electronics Using Advanced embedded Touch Technology" of SID 2018 by Jaehun Jun, yongwoo Choi, hongju Lee, hyeongwon Kang, myungho Shin, junyouun Hwang, hyunkyu Park, kyungjin Jang, joingsang bauk In 2018 on 5/30 th discloses that In a period of a display device, a blank multiplexer is used to select a driving electrode and scan sequentially, and an In-phase pulse signal is applied to a non-driving electrode, a data line, and a gate line.

In the detection method described in japanese patent No. 6501750, although the noise level at the peak frequency may decrease, the noise level at the other frequency band increases. In addition, since the frequency of the driving signal must be switched to a lower frequency than the maximum driving frequency that can be detected by a touch, the number of driving voltages that can be applied during a limited display blank period may be reduced, and touch detection accuracy may be degraded.

In the detection method described in U.S. patent application publication No. 2019/0235663, the display is divided and must be controlled by a display area. Therefore, the scale of the circuit system increases. Further, since the non-display area serves as a touch detection area, timing for touch detection differs from display area to display area, and responsiveness differs from area to area.

The driving method disclosed In "43inch UHD Digital front assembly sys tem Using Advanced In-cell Touch Technology" of SID 2018 is a method for reducing the influence of parasitic capacitance, and does not take into consideration electromagnetic noise. In addition, the non-sense lines and electrodes are driven in phase with the sense lines and electrodes. Therefore, the radiated electromagnetic noise increases.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to maintain accuracy and responsiveness of touch detection while suppressing electromagnetic noise radiated from a touch panel due to driving of touch electrodes.

Disclosure of Invention

In order to achieve the above object, a touch panel according to the present disclosure includes:

a sensor electrode disposed; and

a driver circuit connected to each sensor electrode, wherein

The sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected, and

the driver circuit alternately or sequentially applies a driving voltage to the sensor electrodes in the plurality of groups, detects a capacitance of each sensor electrode, and detects whether there is a touch based on the detected capacitance.

A driving method for a touch panel of the present disclosure is a method for driving a touch panel including arranged sensor electrodes, the driving method including:

grouping the sensor electrodes into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected, and

the driving voltages are applied to the sensor electrodes in a group order, a capacitance of each sensor electrode is detected, and the presence or absence of a touch is detected based on the detected capacitances.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the disclosure.

According to the present disclosure, the sensor electrodes are divided into a plurality of groups, and the driving voltage is applied in units of groups. As such, compared with the case where the sensor electrodes are driven simultaneously, the amount of current caused by the driving pulse can be suppressed, and the electromagnetic noise can be suppressed. In addition, the sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected. As such, unlike when dividing regions and detecting, detection can be performed with good responsiveness, and detection accuracy can be improved.

Drawings

A more complete understanding of the present application may be obtained when the following detailed description is considered in conjunction with the following drawings, in which:

fig. 1 is a schematic configuration diagram of a touch display device according to embodiment 1;

fig. 2 is a configuration diagram of a touch detector of the touch display device shown in fig. 1;

fig. 3 is a configuration diagram of the driver IC shown in fig. 1;

fig. 4 is a timing diagram illustrating an operation of the touch display device shown in fig. 1 and 2;

fig. 5A and 5B are diagrams illustrating a state in which there is a touch of the touch detector shown in fig. 2;

fig. 6 is a configuration diagram of a first modified example of the touch detector according to embodiment 1;

fig. 7 is a configuration diagram of a second modified example of the touch detector according to embodiment 1;

fig. 8 is a configuration diagram of a first example of a touch detector according to embodiment 2;

FIG. 9 is a timing diagram illustrating the operation of the touch display device shown in FIG. 7;

fig. 10 is a configuration diagram of a second example of a touch detector according to embodiment 2;

fig. 11 is a configuration diagram of a third example of the touch detector according to embodiment 2;

fig. 12 is a configuration diagram of a first example of a touch detector according to embodiment 3;

fig. 13 is a configuration diagram of a second example of a touch detector according to embodiment 3;

fig. 14 is a configuration diagram of a third example of the touch detector according to embodiment 3;

fig. 15 is a configuration diagram of a touch detector according to embodiment 4; and

fig. 16 is a diagram showing a frequency spectrum distribution of a near magnetic field by a driving method when a touch electrode is pulse-driven.

Detailed Description

Hereinafter, a touch panel and a driving method for the touch panel according to various embodiments are described while referring to the drawings.

Example 1

A touch panel and a driving method for the touch panel according to embodiment 1 are described while referring to fig. 1 to 5B.

First, a configuration of the touch display device 100 according to the embodiment is described while referring to fig. 1.

Fig. 1 is a schematic system configuration diagram of a touch display device 100. As shown in fig. 1, the touch display device 100 includes a display panel 110 on which a plurality of data lines DL to which data voltages corresponding to video signals are applied and a plurality of gate lines GL to which gate signals are applied are arranged, and the display panel 110 includes a plurality of sub-pixels (sub-pixel electrodes) SP arranged near crossing positions of the data lines DL and the gate lines GL. The data line DL is connected to the sub-pixel SP via a source/drain path of a Thin Film Transistor (TFT), not shown. A data driving circuit, not shown, is connected to each data line DL. Each gate line GL is connected to the gates of a plurality of TFTs of the same column, and to a gate driving circuit, not shown. The data driving circuit applies a data voltage defining a display image of one row to be written to each data line DL. The data voltage is applied to the sub-pixels SP via the TFTs of the row. The gate driver circuit sequentially applies a gate signal for turning on the TFT of the sub-pixel SP connected to the data voltage to be written to each gate line GL.

The touch electrodes TE are arranged in a matrix on substantially the entire surface of the touch detection area of the display panel 110. The touch electrode TE is used to detect contact (touch) by a user or proximity of a body part of the user. The touch electrode TE is an example of a sensor electrode for detecting contact or proximity of an object to be detected.

Fig. 2 shows a configuration of the touch detector 120 of the touch display device 100. Here, to facilitate understanding, an example in which the touch electrodes TE are arranged in five rows and four columns is shown. In order to easily distinguish the touch electrode TE, the touch electrodes of the ith row and jth column are labeled with reference symbols TEij. The touch electrodes TEij are grouped in a repeating pattern of a single unit. Specifically, the touch electrodes TE are divided into two groups in units of columns, i.e., a group GA of the first and third columns and a group GB of the second and fourth columns. Each touch electrode TEij is connected to a driver Integrated Circuit (IC) 11 via a drive signal line SL. The touch electrodes TE are arranged so that sensor electrodes belonging to different groups exist within the size of the object to be detected. In the present embodiment, it is assumed that the object to be detected is a finger of an adult, and that the size of the object to be detected is 5mm × 5mm. In this case, each of the touch electrodes TE is configured by a rectangular transparent electrode having a length/width of 1 to 5mm such that the touch electrodes TE belonging to the two groups are arranged within a size of 5mm × 5mm.

The driver IC 11 is a driver circuit for detecting the presence or absence of a touch and for detecting a touch position. The driver IC 11 is individually connected to each touch electrode TEij via a driving signal line SL.

When detecting the touch position, first, the driver IC 11 applies a positive drive pulse in parallel to the touch electrodes TE of the a group GA, and applies the reference voltage Vc to the touch electrodes TE of the B group GB. The low voltage of the drive pulse is the reference voltage Vc, and the high voltage (drive voltage) is set to a voltage that enables detection of the approach of the object to be detected. However, the driving voltage value is not limited. In one example, the reference voltage Vc is a DC fixed voltage such as a ground voltage, a power supply voltage, or the like. However, any voltage may be used as long as it can prevent the touch electrode TE from being in a floating state and can suppress radiation electromagnetic noise. Note that, in the case where the driver IC 11 is a sensor circuit that detects rising and falling of the drive pulse, by setting the reference voltage Vc to an intermediate value between the high voltage and the low voltage of the drive pulse, the influence from the electrodes of other groups can be equalized in the rising and falling periods, and the detection accuracy can be optimized.

When a finger of a person approaches the touch electrode TE, parasitic capacitances are simultaneously formed between the finger and the one or more touch electrodes TE of the a group GA being approached and between the finger and the one or more touch electrodes TE of the B group GB being approached. When the potential of the finger is stabilized, a current instantaneously flows between the finger and the driven touch electrode TE of the group a GA via the parasitic capacitance. Meanwhile, when the potential of the finger is unstable, a current instantaneously flows from the touch electrodes TE of the driven group a GA to the non-driven touch electrodes TE of the group B GB via the parasitic capacitance and the finger. The driver IC 11 monitors the current flowing through each of the driven drive signal lines SL and the like to detect the parasitic capacitance of each of the driven touch electrodes TE. In one example, the driver IC 11 determines whether there is an approaching finger based on whether the detected parasitic capacitance is larger than a reference value, and identifies the coordinate position (i, j) of the finger from the distribution of the parasitic capacitance when it is determined that there is an approaching finger.

At the next detection timing, the driver IC 11 applies the positive drive pulse to the touch electrodes TE of the B group GB in parallel, and applies the reference voltage Vc to the touch electrodes TE of the a group GA. The driver IC 11 monitors the current flowing through each of the driving signal lines SL, and detects the distribution of the parasitic capacitance of each of the driven touch electrodes TE. Meanwhile, in one example, the driver IC 11 determines whether there is a finger in proximity based on whether the detected parasitic capacitance is larger than a reference value, and identifies the coordinate position (i, j) of the finger from the distribution of the parasitic capacitance when it is determined that there is a finger in proximity.

Thereafter, the driver IC 11 performs the same operation. Specifically, the driver IC 11 repeats the following operations: i) Applying a positive driving pulse to the touch electrodes TE of the a group GA and applying a reference voltage Vc to the touch electrodes TE of the B group GB, detecting a parasitic capacitance of each touch electrode TE of the a group GA by monitoring a current flowing through each driving signal line SL, determining whether a finger exists near the touch electrodes TE of the a group GA by comparing the parasitic capacitance of each touch electrode TE with a reference value, and identifying a coordinate position (i, j) of the finger from a distribution of the parasitic capacitances; and the following operation ii) applies a positive driving pulse to the touch electrodes TE of the B group GB and applies a reference voltage Vc to the touch electrodes TE of the a group GA, detects a parasitic capacitance of each touch electrode TE of the B group GB by monitoring a current flowing through each driving signal line SL, determines whether a finger exists near the touch electrodes TE of the B group GB by comparing the parasitic capacitance of each touch electrode TE with a reference value, and identifies a coordinate position (i, j) of the finger from a distribution of the parasitic capacitances. At the end of the touch detection mode or the like, the driver IC 11 recognizes the coordinate position (i, j) of the finger in the matrix of the touch electrodes TE based on the distribution from the plurality of detections at the time of driving the a group GA and the distribution from the plurality of detections at the time of driving the B group GB, and outputs the coordinate position (i, j) to the host device.

As shown in fig. 3, the driver IC 11 includes: a drive circuit 111, a current detection circuit 112, a capacitance detection circuit 113, a position measurement circuit 114, and a timing controller 115.

The drive circuit 111 applies the drive signal SA shown in fig. 4 to the touch electrodes TE of the a group GA and applies the drive signal SB shown in fig. 4 to the touch electrodes TE of the B group GB via the drive signal lines SL.

The current detection circuit 112 detects a current flowing through each of the driving signal lines SL.

The capacitance detection circuit 113 detects the corresponding capacitance based on the current detected by the current detection circuit 112.

The position measurement circuit 114 recognizes the coordinate position (i, j) of the touched or approached touch electrode TE based on the distribution of the detected capacitances, and outputs the coordinate position (i, j) to the host device.

And a timing controller 115 supplying timing control signals for controlling operation timings of the driving circuit 111, the current detection circuit 112, and the capacitance detection circuit 113.

Next, the operation of the touch display device 100 provided with the above-described configuration is described.

As shown in fig. 4, the touch display device 100 repeats a display mode DM of displaying an image and a touch detection mode TM of detecting a touch position (including a proximity position) in an alternating manner.

In the display mode DM, a gate driver, not shown, sequentially applies gate pulses to the gate lines GL and sequentially turns on the TFTs of each row. The data driver applies a data voltage, which indicates the gray scale of each sub-pixel SP of each row to which the gate pulse is applied by the gate driver, to the data line DL. As a result, the gradation of each sub-pixel SP is set and maintained for one frame period. An image is displayed by repeating such an operation for all the sub-pixels SP.

When the operation mode is shifted from the display mode DM to the touch detection mode TM, the driver IC 11 starts the touch detection operation.

First, as shown in fig. 2, the driver IC 11 groups the touch electrodes TE into a group a GA and a group B GB. However, at this stage, it is not necessary to newly group the touch electrodes TE. For example, it is sufficient to perform processing when a group is set at the design stage of the driver IC 11. In the present disclosure, the concept of "grouping" includes such a case.

The driving circuit 111 of the driver IC 11 applies the driving signal SA shown in fig. 4 to the touch electrodes TE of the a group GA and applies the driving signal SB shown in fig. 4 to the touch electrodes TE of the B group GB according to the control of the timing controller 115. The drive signals SA and SB are signals configured by a series of positive drive pulses DP that are offset from each other by a phase of about pi. The pulse width of each drive pulse is, for example, from 3 to 7 μ s, and in the present example, 5 μ s. In this case, the pulse period is, for example, 15 μ s, which is three times the pulse width. In addition, the current detection circuit 112 of the driver IC 11 detects a current flowing through each of the driving signal lines SL, that is, detects a current flowing through each of the touch electrodes TE, according to the control of the timing controller 115.

As shown in fig. 5A and 5B, it is assumed that the finger 21 is approaching a position above and between the touch electrode TE32 and the touch electrode TE 33. In this case, a parasitic capacitance is formed between the finger 21 and the adjacent touch electrode TE. The magnitude of the parasitic capacitance varies depending on the distance between the finger 21 and each touch electrode TE. In fig. 5A and 5B, to facilitate understanding, a parasitic capacitance C1 between the touch electrode TE32 and the finger 21 and a parasitic capacitance C2 between the touch electrode TE33 and the finger 21 are illustrated. In addition, the touch electrode TE to which the driving pulse DP is applied is shown by hatching.

According to the control of the timing controller 115, the driving circuit 111 of the driver IC 11 applies the driving pulse DP of the driving signal SA to the a group GA, i.e., to the touch electrodes TE of the first and third columns, and applies the reference voltage Vc of the driving signal SB to the B group GB, i.e., to the touch electrodes TE of the second and fourth columns. Then, when the human finger 21 is approaching the touch electrode TE, a current instantaneously flows through the touch electrode TE33 and the surrounding touch electrode TE via the parasitic capacitance C2 and the human body or the parasitic capacitance C2, the finger 21, and the parasitic capacitance C1. The current detection circuit 112 of the driver IC 11 detects a current flowing through each of the driving signal lines SL according to the control of the timing controller 115. The capacitance detection circuit 113 obtains the distribution of the parasitic capacitance from the distribution of the current. The position measurement circuit 114 obtains the position coordinates (i, j) of the finger from the obtained capacitance distribution, and outputs the position coordinates (i, j).

Next, according to the control of the timing controller 115, as shown in fig. 4 and 5B, the driving circuit 111 of the driver IC 11 applies the driving pulse DP of the driving signal SB to the B group GB, i.e., to the touch electrodes TE of the second and fourth columns, and applies the reference voltage Vc of the driving signal SB to the a group GA, i.e., to the touch electrodes TE of the first and third columns. Then, when the human finger 21 is approaching the touch electrode TE, a current instantaneously flows through the touch electrode TE32 and the surrounding touch electrode TE via the parasitic capacitance C1 and the human body or the parasitic capacitance C1, the finger 21, and the parasitic capacitance C2. The current detection circuit 112 of the driver IC 11 detects a current flowing through each of the driving signal lines SL according to the control of the timing controller 115. The capacitance detection circuit 113 obtains the distribution of the parasitic capacitance from the distribution of the current. The position measurement circuit 114 obtains the obtained capacitance distribution, obtains position coordinates (i, j) of the finger from the obtained capacitance distribution, and outputs the position coordinates (i, j).

The driver IC 11 repeats the same operation a plurality of times, and when the driver 11 can determine that there is no erroneous detection caused by external noise or the like, outputs the position coordinates (i, j) finally calculated from the coordinates detected when the a-group GA is driven and from the coordinates detected when the B-group GB is driven to the host device. Any calculation method may be used. Examples include using averages and using majority blocks.

Thereafter, the operation mode transitions to the display mode DM. During the display mode DM period, the driver IC 11 does not perform constant potential output or pulse output as a noise source in a high impedance state.

According to the above-described configuration and touch detection operation, the number of driven electrodes can be halved and the radiated electromagnetic noise can be halved, as compared to when a driving method is used in which all the touch electrodes TE are driven simultaneously and simultaneously. In addition, the entire touch detection area can be detected substantially simultaneously, and a reduction in touch detection accuracy does not occur due to the division of the driving area.

A pulse voltage is applied to the touch electrodes TE to be driven, and a reference voltage Vc is applied to the touch electrodes TE not to be driven. In this manner, the electromagnetic shielding effect of the touch electrode TE and the driving signal line SL can be obtained. Further, when the finger 21 is approaching, a parasitic capacitance is also generated between the touch electrodes TE in the constant voltage state. As such, even when the finger 21 is in an electrically floating state and is unstable, it is possible to accurately determine whether or not the finger 21 is present, and to accurately determine the position thereof when the finger 21 is present.

Note that although an example is given in which the finger 21 is detected, any object to be detected may be used as long as a parasitic capacitance can be formed between the touch electrode TE and the object to be detected. Examples include a part of a living organism, a stylus, a touch pen, and the like. Note that the size and grouping of the touch electrodes TE are set according to the size of the object to be detected, so that different groups of sensor electrodes are set within the size of the object to be detected.

Although an example is given in which the display mode DM and the touch detection mode TM are set in an alternating manner, the modes may be set in any manner.

Although an example in which the touch panel is a touch display device provided with a display function is described, the touch panel may be a touch panel dedicated to touch detection and not provided with a display function.

The driver IC may have any configuration as long as the above-described position determination can be performed. For example, the driver IC may have a configuration for detecting a current distribution, and the external device may determine the distribution of capacitance and the position of the finger.

In the above-described embodiment, the touch electrodes TE are grouped in a repeating pattern in units of a single row. Because of this, the touch electrodes TE are grouped such that each of the plurality of sensor electrodes is adjacent to at least one sensor electrode belonging to the other group. However, the present disclosure is not limited thereto. For example, a configuration is possible in which the touch electrodes TE are grouped in a pattern that repeats every other row, and the drive pulses are applied in an alternating manner, as in the touch detector 121 shown in fig. 6. The drive signals in this case may be the same as those shown in fig. 4 and 4. Note that, in fig. 6, in order to facilitate understanding of the grouping of the touch electrodes TE, the same hatching marks are used for the touch electrodes TE of the same group. The same applies to the following figures.

In the description given above, an example is given in which the touch electrodes TE are grouped in a repetitive pattern of a plurality of detection units (such as in row units or in column units). However, the present disclosure is not limited thereto. For example, a configuration is possible in which, as with the touch detector 122 shown in fig. 7, the touch electrodes TE are grouped in a repeating pattern of a single unit (i.e., grouped in a checkered pattern), and the drive pulses are applied in an alternating manner. The drive signals in this case may be the same as those shown in fig. 4 and 4.

Example 2

In the description given above, an example is given in which the touch electrodes TE are divided into two groups and the drive pulses are applied in an alternating manner. However, the present disclosure is not limited thereto. A configuration is possible in which the touch electrodes TE are divided into n groups, where n is an arbitrary natural number greater than or equal to 2, and the drive pulses are sequentially applied in units of groups. Hereinafter, an example of the number of groups n =3 is described.

In the touch detector 123 of fig. 8, an example is shown in which the touch electrodes TE are divided into three groups (i.e., a group a GA, a group B GB, and a group C GC) in units of columns. As shown in fig. 8, the touch electrodes TE of the first and fourth columns are grouped into a group a GA, the touch electrodes TE of the second and fifth columns are grouped into a group B GB, and the touch electrodes TE of the third and sixth columns are grouped into a group C GC. With this configuration, the touch electrodes TE are arranged so that the touch electrodes TE belonging to the three groups GA, GB, and GC can exist within the size range of the object to be detected. In one example, when the width of the finger 21 is 5mm, the touch electrode TE is set such that the width of the touch electrode TE × 3 <5mm.

As shown in fig. 9, the driver IC 11 sequentially applies the drive pulses to the groups in the order of the touch electrodes TE of the a group GA → the touch electrodes TE of the B group GB → the touch electrodes TE … of the C group GC, and applies the reference voltage Vc to the non-driven touch electrodes TE. In other words, in one frame, all the touch electrodes TE are driven in three applications of the driving pulse while the touch electrodes TE are switched.

In the touch detector 124 of fig. 10, an example is shown in which the touch electrodes TE are divided into three groups (i.e., a group a GA, a group B GB, and a group C GC) in units of rows. As shown in fig. 10, the touch electrodes TE of the first and fourth rows are grouped into a group a GA, the touch electrodes TE of the second and fifth rows are grouped into a group B GB, and the touch electrodes TE of the third and sixth rows are grouped into a group C GC. As shown in fig. 9, the driver IC 11 sequentially applies driving pulses in the order of the touch electrodes TE of the a group GA → the touch electrodes TE of the B group GB → the touch electrodes TE. of the C group GC, and applies the reference voltage Vc to the non-driven touch electrodes TE.

Further, in the touch detector 125 of fig. 11, an example in which the touch electrodes TE are divided into three groups (i.e., a group a GA, a group B GB, and a group C GC) in a single unit is shown. As shown in fig. 9, the driver IC 11 sequentially applies driving pulses in the order of the touch electrodes TE of the a group GA → the touch electrodes TE of the B group GB → the touch electrodes TE. of the C group GC, and applies the reference voltage Vc to the non-driven touch electrodes TE.

According to the configuration of embodiment 2, the radiated electromagnetic noise in embodiment 1 or more can be reduced. In addition, as in embodiment 1, an electromagnetic shielding effect can be obtained, and a finger or the like in a floating state can be detected more accurately.

Example 3

When the number of the sensor electrodes TE increases, there is a possibility that false detection will occur due to a coupling effect between the sensor electrodes TE. In the present embodiment, in the grouping every n rows, every n columns, or every n unit cells, the detection results of the touch electrodes TE adjacent to the touch electrodes TE of the other groups are not used in the position detection, and the detection results of the non-adjacent touch electrodes TE are used only for detecting the object to be detected. As a result, the coupling effect between the touch electrodes TE is reduced. Note that n.gtoreq.3.

The touch detector 126 of fig. 12 shows an example of a unit in which the touch electrodes TE are grouped into three columns. Specifically, the touch electrodes TE of the first to third columns are grouped into a group GA, and the touch electrodes TE of the fourth to sixth columns are grouped into a group GB. Note that, also in this example, it is desirable that the touch electrode TE is set so that the width of one of the groups GA, GB < the size of the object to be detected.

The driver IC 11 applies the driving signals SA shown in fig. 4 to the touch electrodes TE of the a-group GA in parallel (i.e., to the touch electrodes TE of the first to third columns), and applies the driving signals SB shown in fig. 4 to the touch electrodes TE of the B-group GB in parallel (i.e., to the touch electrodes TE of the fourth to sixth columns).

To perform touch detection, the driver IC 11 uses the touch electrodes TE of the respective second columns of the groups GA, GB except for the outermost column, that is, the second and fifth columns. The touch electrodes TE for touch detection are shown by hatching marks. More specifically, the driver IC 11 uses only the current instantaneously flowing to the touch electrodes TE of the second and fifth columns to detect a touch or approach, and although the driver IC 11 applies the driving signal SA or SB to the touch electrodes TE of the first, third, fourth, and sixth columns, the current flowing to these touch electrodes TE is not detected and is not used in touch detection. Hereinafter, a touch electrode that detects a current and is used in touch detection is referred to as an active electrode, and a touch electrode that is applied with a driving signal but does not detect a current and is not used in touch detection is referred to as an inactive electrode.

Next, a touch detection operation of the touch detector 126 is described.

The driver IC 11 applies the driving signal SA shown in fig. 4 to the touch electrodes TE of the a group GA, and applies the driving signal SB shown in fig. 4 to the touch electrodes TE of the B group GB.

At the timing when the driver IC 11 applies the driving pulse to the touch electrodes TE of the a group GA and the reference voltage Vc to the touch electrodes TE of the B group GB, the driver IC 11 detects the current flowing through each of the driving signal lines SL connected to the touch electrodes TE of the second column, obtains the distribution of the current (i.e., the distribution of the parasitic capacitance), and obtains the position coordinates (i, j) of the finger from the obtained distribution.

Then, at the timing when the driver IC 11 applies the reference voltage Vc to the touch electrodes TE of the a group GA and applies the driving pulse to the touch electrodes TE of the B group GB, the driver IC 11 detects the current flowing through each of the driving signal lines SL connected to the touch electrodes TE of the fifth column, obtains the distribution of the current (i.e., the distribution of the parasitic capacitance), and obtains the position coordinates (i, j) of the finger from the obtained distribution.

While in the touch detection mode, the driver IC 11 repeats the same operation.

The touch detector 127 of fig. 13 shows an example of a unit in which the touch electrodes TE are grouped into three rows. Specifically, the touch electrodes TE of the first to third rows are grouped into a group GA, and the touch electrodes TE of the fourth to sixth rows are grouped into a group B GB. Note that, also in this example, it is desirable that the touch electrode TE is set so that the width of one of the groups GA, GB < the size of the object to be detected.

The driver IC 11 applies the driving signals SA shown in fig. 4 to the touch electrodes TE of the a group GA in parallel, and applies the driving signals SB shown in fig. 4 to the touch electrodes TE of the B group GB in parallel.

The driver IC 11 sets only the touch electrodes TE of the second and fifth rows, through which the current instantaneously flows, as active electrodes used in the detection of touch or proximity, and sets the touch electrodes TE of the first, third, fourth, and sixth rows as inactive electrodes not used in the touch detection.

In the touch detector 128 of fig. 14, each unit of the touch electrodes TE is constituted by nine touch electrodes TE arranged in three columns and three rows. The plurality of units are divided into groups GA and GB such that adjacent units belong to different groups. Of three columns and three rows of touch electrodes TE constituting one unit, the touch electrode TE located at the center is set as an active electrode used in touch detection, and the touch electrodes TE around eight are set as inactive electrodes. The driver IC 11 applies the driving signals SA shown in fig. 4 to the touch electrodes TE of the group GA in parallel, and applies the driving signals SB shown in fig. 4 to the touch electrodes TE of the group GB in parallel.

At the timing when the driver IC 11 applies the driving pulse to the touch electrodes TE of the group GA and the reference voltage Vc to the touch electrodes TE of the group GB, the driver IC 11 detects the touch electrodes TE at the center of each unit (i.e., detects the current flowing through each of the driving signal lines SL connected to the touch electrodes TE22 and TE 55), obtains the distribution of the current (i.e., the distribution of the parasitic capacitance), and obtains the position coordinates (i, j) of the finger. Then, at the timing when the driver IC 11 applies the driving pulse to the touch electrodes TE of the group GB and the reference voltage Vc to the touch electrodes TE of the group GA, the driver IC 11 detects the touch electrodes TE at the center of each unit (i.e., detects the current flowing through each of the driving signal lines SL connected to the touch electrodes TE52 and TE 25), and obtains the position coordinates (i, j) of the finger. Thereafter, the driver IC 11 repeats the same operation while in the touch detection mode TM, and outputs the finally detected position.

According to the touch detector of embodiment 3, the coupling effect between the touch electrodes TE can be reduced, and the detection accuracy can be improved.

Note that a configuration in which n is greater than or equal to 4 is possible. In this case, the coordinate detection is performed with the touch electrodes TE not adjacent to the touch electrodes TE of other units as the effective electrodes and the touch electrodes TE adjacent to the touch electrodes TE of other units as the ineffective electrodes.

Example 4

When the number of the groups is large, the number of the touch electrodes TE driven at the same time is reduced, and the radiated electromagnetic noise is reduced. However, since the touch electrode TE must be switched to be driven, the detection time increases. The display blank period differs depending on the input video signal, and as such, the number of packets can be switched to obtain a touch detection period corresponding to the video signal.

For example, in the touch detector 129 of fig. 15, the detector 13 (such as a noise detector or an operation mode detector) is connected to the driver IC 11. A configuration is possible in which, when the detector 13 detects electromagnetic noise of a magnitude greater than or equal to a reference value and/or in the case of a predetermined operation mode in which electromagnetic noise is likely to be generated, for example, in order to suppress generation of electromagnetic noise, the detector 13 divides the touch electrodes TE into N groups and drives the touch electrodes TE individually; and when the detector 13 detects electromagnetic noise of a magnitude smaller than the reference value and/or in the case of a predetermined operation mode in which the electromagnetic noise is unlikely to be generated, the detector 13 outputs a control signal to the driver IC 11, the control signal decreasing the division number N so as to allow an increase in the electromagnetic noise.

A configuration is possible in which the driver IC 11 increases the division number N to suppress noise when no touch is detected for the reference period or longer. In this case, it is sufficient that the driver IC 11 includes a timer, for example, the timer is reset when a touch is detected, and the division number N is switched when the timer counts to a reference value.

Any grouping of the touch electrodes TE may be used as long as electrodes belonging to different groups are included in a range smaller than an object to be detected (such as a finger). For example, any combination of embodiments 1 to 4 may be used, a configuration in which three or more groups are provided is possible, and a configuration in which the number of divisions N is greater than or equal to 3 is possible. Such a configuration enables the grouping corresponding to the operating environment to be performed. For example, when a touch panel is incorporated into the apparatus a, a configuration is possible in which, in a case where the grouping shown in fig. 2 is not desired for various reasons, the detector 13 detects that the touch panel is incorporated into the apparatus a and outputs a control signal, and the driver IC 11 uses the grouping method shown in fig. 15 instead of the grouping method shown in fig. 2. In addition, a configuration is possible in which, when there is a parasitic capacitance between the drive signal line SL and the touch electrode TE, the grouping method is selected based on the parasitic capacitance detected by the detector 13 so as to reduce the influence of the parasitic capacitance. In addition, a configuration is possible in which the control signal is supplied to the driver IC 11 based on a user command.

Fig. 16 shows the result of measuring the near magnetic field of the touch panel surface when the touch electrode is pulse-driven. By measuring the near magnetic field of the touch panel, the magnitude of the spike current flowing through the touch panel and its frequency components can be confirmed. The magnetic field strength is shown on the vertical axis in dB and the frequency Hz on the horizontal axis. (1) and (2) assume typical touch panel driving conditions. (1) Is the case where all touch electrodes are driven by a 100kHz pulse signal, and (2) is the case where all touch electrodes are driven by a 50kHz pulse signal. (3) Assume a touch panel driving condition in which the driving frequency is variable, and the frequency of the pulse signal is changed from 50kHz to 100kHz in steps at 5 kHz. (4) The touch panel driving condition of the present disclosure (for example, TM period of fig. 3) is simply simulated, and a case is shown in which a 50kHz pulse signal is applied to one half of the touch panel electrodes and a constant potential is applied to the other half, and the driving state of each half of the touch panel electrodes alternates.

In the measurement result (4) shown in fig. 16, the magnetic field strength at a frequency lower than 1MHz is lower than other measurement results. Even in the frequency band higher than 1MHz, the magnetic field strength was less than or equal to the measurement results obtained using the other driving methods, and no deterioration was observed. Accordingly, it was confirmed that the driving method for the touch panel of the present disclosure can suppress the spike current flowing through the touch panel and can control the frequency component of the spike current waveform. In other words, embodiments of the present disclosure provide a touch panel and a control method for a touch panel that can suppress electromagnetic noise radiated from the touch panel and control the frequency of the electromagnetic noise.

The embodiments of the present disclosure are described above, but the present disclosure is not limited to these embodiments.

In the above-described embodiment, a description is given in which the current instantaneously flowing through the touch electrode TE to which the driving pulse is applied is detected to detect the capacitance of the touch electrode TE, thereby detecting the object to be detected. However, methods other than detecting current may be used. For example, a configuration is possible in which an arbitrary physical quantity (such as the amount of charge stored in the touch electrode and the detection of the capacitance of the touch electrode TE) that varies depending on the magnitude of the capacitance formed between the object to be detected and the touch electrode TE is set as the detection target.

In the above-described embodiment, the reference voltage Vc is applied to the non-drive electrode TE, but a configuration in which the non-drive electrode is set to a floating state or an AC voltage is applied to the non-drive electrode is possible. However, a fixed DC reference voltage is desirable.

For example, a configuration is possible in which the touch detection device does not include a display function. In addition, the grouping of the touch electrodes is not limited to the above-described example. That is, any grouping method may be used as long as the touch electrodes TE arranged in the area to be detected can be grouped such that each of the touch electrodes TE is adjacent to at least one electrode TE belonging to another group.

In the above-described embodiment, the driver IC 11 performs detection of the presence or absence of touch and detection of a touch position. However, a configuration is possible in which the driver IC 11 transmits the capacitance distribution detected in each detection process to the host device, and the host device is responsible for identifying whether or not there is a touch, and identifying a touch position when there is a touch. The division of roles between the driver IC 11 and the host device can be set as desired.

In the above-described embodiment, in the touch detection mode TM, the number of drive pulses applied to each set of touch electrodes TE is set to 8, but the number of pulses may be set as desired. However, it is preferable to set the number of pulses to 5 or more from the viewpoint of detection accuracy. In addition, the pulse width, the pulse duty ratio, and the like may be set as desired. Further, it is sufficient to appropriately set the voltage (pulse height) of the driving pulse within a range in which a touch can be detected and also electromagnetic noise can be suppressed. Positive pulses are described for the drive pulses, but the polarity of the drive pulses can be set as desired.

The driver IC may be implemented as a semiconductor device, a discrete circuit, or as a processor controlled by software.

The foregoing description of certain exemplary embodiments has been presented for purposes of illustration. Although the foregoing discussion has set forth specific embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims (11)

1. A touch panel, comprising:

a sensor electrode disposed; and

a driver circuit connected to each of the sensor electrodes, wherein

The sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected, and

the driver circuit alternately or sequentially applies a driving voltage to the sensor electrodes in the plurality of groups, detects a capacitance of each of the sensor electrodes, and detects whether there is a touch based on the detected capacitance.

2. The touch panel according to claim 1, wherein the driver circuit applies a reference voltage to sensor electrodes in a group to which the driving voltage is not applied.

3. The touch panel according to claim 1 or 2, wherein

The sensor electrodes are arranged in a matrix and are each grouped so as to be adjacent to at least one of the sensor electrodes belonging to another group, and

the driver circuit alternately or sequentially applies the driving voltage to the sensor electrodes in the plurality of groups.

4. The touch panel according to any one of claims 1 to 3, wherein the sensor electrodes are alternately grouped in one or the other of two groups in a column unit, a row unit, or individually.

5. The touch panel according to any one of claims 1 to 3, wherein

The sensor electrodes are arranged in a matrix and grouped into three groups such that every other sensor electrode belongs to a different group, an

The driver circuit sequentially applies the driving voltages to the sensor electrodes in units of groups.

6. The touch panel according to claim 5, wherein the sensor electrodes are grouped in any one of three groups in a row unit, a column unit, or individually in order.

7. The touch panel according to claim 1 or 2, wherein

The sensor electrodes are arranged in a matrix.

One unit is constituted by a plurality of the sensor electrodes, grouping is performed so that adjacent units belong to different groups, and

the driver circuit detects whether there is a touch based on a capacitance of a sensor electrode not adjacent to another unit among the sensor electrodes of each unit.

8. The touch panel according to claim 7, wherein the sensor electrodes form a unit of three columns, a unit of three rows, or a unit of three columns by three rows.

9. The touch panel according to any one of claims 1 to 8, wherein the driver circuit switches the grouping of the plurality of sensor electrodes.

10. The touch panel according to claim 9, wherein the driver circuit switches the grouping in any of when commanded by a control signal, when no touch is detected within a reference period, when an operation mode of an electronic device provided with the touch panel is in a specific operation mode, and when radiated electromagnetic noise of the touch panel is greater than or equal to a reference value.

11. A driving method for a touch panel including arranged sensor electrodes, the driving method comprising:

grouping the sensor electrodes into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than an object to be detected; and is provided with

The driving voltage is applied to the sensor electrodes in a group order, a capacitance of each of the sensor electrodes is detected, and whether there is a touch is detected based on the detected capacitances.

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